Clowney's physical skills, on the other hand, aren't a question for Mayock. In fact, he sees more potential in Clowney than he did in a former No. 1 overall pick of the Texans at the same position, Mario Williams.

"I know that he's got the physical makeup to be the best player the draft," Mayock said. "If you want to compare him to Mario Williams, I think he's a better football player with more upside than when Mario came out of college. ... From a physical skill-set (standpoint), this kid is as freaky as they come. He plays a position of critical importance in today's NFL, which is an ability to get the quarterback, and he can play multiple places on the defense. All those things check off."

NFL scouts have questioned the consistency of Clowney's effort, and his game-day decision not to play against Kentucky last fall without following the Gamecocks' protocol of communication with trainers during the practice week only spurred questions about his motivation.

"My biggest concern is just, what's his mental makeup?" Mayock said. "How important is it to him, when he gets a paycheck, to become the best player in football, or is he just going to be happy to be a millionaire? I think that's the most critical checking point here for an organization, is finding out the motivation. What kind of kid are they going to get? I know what the football player is when motivated. I just want to know what kind of kid I'm getting."

Clowney is considered a possibility for the Texans with the top overall pick, but with Houston having a need at quarterback and an elite pass rusher already in place in J.J. Watt, Clowney could easily be available to the St. Louis Rams at No. 2.